Computers

A computer is a machine (Opens in a new window) that can be programmed to carry out (Opens in a new window) sequences of arithmetic (Opens in a new window) or logical operations (Opens in a new window) (computation (Opens in a new window)) automatically. Modern digital electronic (Opens in a new window) computers can perform generic sets of operations known as programs (Opens in a new window). These programs enable computers to perform a wide range of tasks. A computer system is a nominally complete computer that includes the hardware (Opens in a new window), operating system (Opens in a new window) (main software (Opens in a new window)), and peripheral (Opens in a new window) equipment needed and used for full operation. This term may also refer to a group of computers that are linked and function together, such as a computer network (Opens in a new window) or computer cluster (Opens in a new window).

A broad range of industrial (Opens in a new window) and consumer products (Opens in a new window) use computers as control systems (Opens in a new window). Simple special-purpose devices like microwave ovens (Opens in a new window) and remote controls (Opens in a new window) are included, as are factory devices like industrial robots (Opens in a new window) and computer-aided design (Opens in a new window), as well as general-purpose devices like personal computers (Opens in a new window) and mobile devices (Opens in a new window) like smartphones (Opens in a new window). Computers power the Internet (Opens in a new window), which links billions of other computers and users.

Early computers were meant to be used only for calculations. Simple manual instruments like the abacus (Opens in a new window) have aided people in doing calculations since ancient times. Early in the Industrial Revolution (Opens in a new window), some mechanical devices were built to automate long, tedious tasks, such as guiding patterns for looms (Opens in a new window). More sophisticated electrical machines did specialized analog (Opens in a new window) calculations in the early 20th century. The first digital (Opens in a new window) electronic calculating machines were developed during World War II (Opens in a new window). The first semiconductor (Opens in a new window) transistors (Opens in a new window) in the late 1940s were followed by the silicon (Opens in a new window)-based MOSFET (Opens in a new window) (MOS transistor) and monolithic integrated circuit (Opens in a new window) chip technologies in the late 1950s, leading to the microprocessor (Opens in a new window) and the microcomputer revolution (Opens in a new window) in the 1970s. The speed, power and versatility of computers have been increasing dramatically ever since then, with transistor counts (Opens in a new window) increasing at a rapid pace (as predicted by Moore's law (Opens in a new window)), leading to the Digital Revolution (Opens in a new window) during the late 20th to early 21st centuries.

Conventionally, a modern computer consists of at least one processing element (Opens in a new window), typically a central processing unit (Opens in a new window) (CPU) in the form of a microprocessor, along with some type of computer memory (Opens in a new window), typically semiconductor memory (Opens in a new window) chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information (Opens in a new window). Peripheral devices include input devices (keyboards, mice, joystick (Opens in a new window), etc.), output devices (monitor screens, printers (Opens in a new window), etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen (Opens in a new window)). Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be saved and retrieved.

Etymology